You click on "My Profile" at the top of the screen and then select "Edit Display" from the drop down menu. That takes you to a new page. Towards the bottom of that page you'll see an option that says "Forum Skin". And you can select from 5 or 6 different versions. Having tried them all out, I've actually ended up going back to the default one!!! But if I'm in a particularly pink mood, I will definitely select Tulip one day!!!